In 1995, we developed a sensitive and specific method for the analysis of bacterial lipopolysaccharides (LPS) including meningococcal LOS on the nylon membrane, Hybond-N, obtained from Amersham. However, the company discontinued the product due to a patent dispute and the new product (bearing the same) worked very poorly in detecting LPSs. After an extensive search for a replacement membrane from different companies and different matrices, we have found that the nylon membrane, MAGNA, from Micron Separations Inc. (MSI) worked as well as the old Hybond-N from Amersham in terms of sensitivity and specificity. Ten to twenty ng of Pseudomonas aeruginosa LPS or meningococcal LOS were detectable with no nonspecific staining of proteins. The LPS patterns obtained by this method were similar to those obtained by silver stain. This chemical detection in combination with antibody detection of an LPS blotted on the same piece of membrane provides a precise way to pinpoint the LOS species binding antibody among multiple components in an LPS or LOS.